The carbon cycle• Trace the pathways through which carbon is released

and absorbed in the diagram below:

• Nitrogen is important to living things because it is used to make amino acids, the building blocks of all proteins.

• Approximately 78 percent of Earth’s atmosphere is nitrogen gas (N2).

The nitrogen cycle

• Phosphorus is essential for cell replication, metabolism, and structures.

• Phosphorus from minerals is absorbed by the roots for use by the plant.

• Animals obtain phosphorus by eating plants.

The phosphorus cycle

The Potassium CycleAnimal

manuresand biosolids

Mineralfertilizers

Crop harvest

Runoff anderosion

Leaching

Soil solution potassium (K+)

Plant residues

Plantuptake

Mineralpotassium

Fixedpotassium

Exchangeable potassium

Input to soilComponent Loss from soil

The Sulfur Cycle

Animalmanures

and biosolids

Mineralfertilizers

Crop harvest

Runoff anderosion

Leaching

Absorbed ormineral sulfur

Plant residues

Plantuptake

SulfateSulfur(SO4)

Atmosphericsulfur

Elementalsulfur

Organicsulfur Immobilization

Immobilization

MineralizationMineralization

Bacterial reduction

Bacterial reduction

Bacterial oxidation

Bacterial oxidationOxid

atio

n

Oxid

atio

n

SOSO22 gas gas

Reduced sulfur

Input to soilComponent Loss from soil

VolatilizationAtmosphericdeposition

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On your computer check this out!

• http://climate.nasa.gov/